38ka以来海南岛东海岸风成沙的粒度特征及其反映的沉积环境演变过程

Grain-size Features of Aeolian Sands on Eastern Coast of Hainan Island and the Reflected Sedimentary Environment since 38 ka BP

木堆地层剖面是海南岛东海岸沙丘与丘间地沉积过程的典型记录。在对该剖面地层高密度采样和光释光定年的基础上,对风成沙及相关沉积物的粒度组成、粒度参数和概率累积曲线及粒度敏感指标(SC/D值)的分析表明,风成沙、弱沙质古土壤、风水两相沉积物和泻湖相沉积物的粒度特征各异,反映38 ka BP来海南岛东海岸沉积环境经历了阶段Ⅰ(38～22 ka BP)、阶段Ⅱ(22～17 ka BP)、阶段Ⅲ(17～10 ka BP)、阶段Ⅳ(10 ka BP至今)等4个演变阶段,气候环境经历了暖湿—暖干—暖湿—暖干—暖湿—干凉—温湿—波动—暖湿的演变,沉积环境也经历了泻湖沉积—沙丘与丘间地沉积—沙丘固定成壤—流沙沉积的演变过程。

The Mudui stratigraphic section is a typical record of the sedimentary process of sand dunes and the inter-lowland in the eastern coast of China＇s Hainan Island. Analyses to grain-size composition, parameters, cumulative probability curve and sensitive indexes （ SC/D value） were conducted based on high-resolution sampling and OSL age determination. Results show that the grain-size features of eolian sands, imma- ture sandy paleosol, sediments of Aeolian-water and lacustrine facies are different from each other. The sedimentary environment evolution in eastern coast of Hainan Island can be divided into four phases： 38-22 ka BP; 22-17 ka BP; 17-10 ka BP; 10 ka BP to present. Correspondingly, climate followed changes of hot-wet-hot-dry-hot-wet-hot-dry-hot-wet-dry-cool-warm-wet-fluctuation-hot-wet; semimetal environment followed changes of lagoon-dune and inter-dune-dune fixed for pedogenic environment-shifting sand deposit.